A curved live roller conveyor consists of a series of rollers which are arranged in a curved path or arc with the axes of the rollers located at an acute angle with respect to each other. The rollers are power driven so that the load supported on the rollers is conveyed by rotation of the rollers.
Problems have arisen in the past in designing an effective drive mechanism for live rollers that are positioned in a curved section of the conveyor. Previous attempts have involved the use of gear trains, chain and sprocket drives, or belt drives to interconnect the rollers in the curved path. However, such drives have been complicated, expensive, and noisy in operation.
As an example, U.S. Pat. No. 4,485,913 shows a drive mechanism for a curved live roller conveyor in which a drive belt is connected to the inner ends of the rollers in the curved path. In this patent the drive belt is mounted on a series of pulleys and the inner end of each roller is engaged with the upper surface of the belt to provide a frictional driving connection between the belt and the rollers.
In U.S. Pat. No. 1,975,927 a belt is frictional engaged with the lower surface of each roller in the curved path, and the belt is mounted to move in a generally curved path beneath the rollers by angularly mounted idler rollers.
In French Pat. No. 1,518,326, a drive belt is mounted for travel in a generally curved path beneath a series of rollers which are biased upwardly out of engagement with the drive belt. The weight of the product on the drive rollers forces the rollers downwardly against the biasing force to bring the rollers into engagement with the belt to thereby provide a driving connection between the belt and the rollers.
In general, the drive systems, as disclosed in the aforementioned patents have included a drive belt that engaged the lower surface of the rollers and the frictional resistance between the belt and the rollers was increased by the weight of the product being conveyed. Conveyors of this type are best suited for heavier products where an increase in weight will provide a corresponding increase in the frictional driving connection.